If the numerical coefficient of the pth term in expansion of (2x+3)^6 is 4860,then value of p is/are?

pth term in the expansion of (2x+3)6 is Cp-16.(2x)6-(p-1).3p-1
=Cp-16.27-p.3p-1.x7-p .......(1)

let us find the factor of 4860 ; 4860=22*35*5 .......(2)
the maximum exponent of 3 which will divide Cr6 is 2.

now comparing the exponent of 3 from (1) and (2):
now for p -1=5 , i.e. p=6 the numerical coefficient  is C56.21.35

for p-1 = 4 i.e. p =5
the numerical coefficient is C46.22.34=6*52*4*81=22*35*5
therefore numerical coefficient of 5th term is 4860.

hope this helps you

 

  • -1
What are you looking for?